In an air-conditioning apparatus serving as a refrigeration cycle apparatus, a heating operation is performed by operating, as an evaporator, an outdoor heat exchanger provided in an outdoor unit so as to remove heat from outdoor air (external air) and to draw the heat into an indoor unit.
For this reason, for example, when the outdoor air temperature is low (for example, the dry-bulb temperature is 2 degrees C. and the wet-bulb temperature is 1 degree C. under the JIS low heating temperature condition), the surface temperature of the outdoor heat exchanger becomes 0 degrees C. or less, and this causes a frosting phenomenon in which moisture in the air flowing into the outdoor heat exchanger adheres as frost to the surface of the outdoor heat exchanger (hereinafter, a condition of the outdoor air temperature under which this frosting phenomenon occurs is referred to as “a low outdoor-air temperature condition”).
If this frosting phenomenon occurs in the outdoor heat exchanger, a part of the outdoor heat exchanger is covered with frost, and this increases the ventilation resistance caused in the air when the air passes through the outdoor heat exchanger. The amount of air flowing into the outdoor heat exchanger is thereby decreased, and as a result, the heating capacity of the air-conditioning apparatus sometimes decreases. Accordingly, in the air-conditioning apparatus, for example, a defrosting operation for removing frost adhering to the outdoor heat exchanger is performed by heating the outdoor heat exchanger with separate heating means. However, the heating operation needs to be stopped during defrosting operation for melting the frost. Thus, when the defrosting operation is performed, comfort in the room serving as an air-conditioned space is deteriorated.
To solve this problem, there has been proposed a method for suppressing frosting caused in an outdoor heat exchanger under a low outdoor-air temperature condition by forming, on a surface of the outdoor heat exchanger, a frosting suppressing layer that enhances water slip performance and water repellency and suppresses frosting (see, for example, Patent Literature 1).